I am not sure what is the philosophical question here. Of course there is no general moral principle that guides the rules that you're evoking and you may imagine a huge cultural variation in different legal systems. There are legal systems which do not recognize the right to abort to a woman who doesn't want to have a child as well as there are legal systems (actually, most of them until recently) that do not oblige a man to support his child if, for example, the child is born outside a legal mariage. The rights of women to decide upon the destiny of their future children seems a very recent contingency of some of the contemporary legal systems, and not an inevitable consequence of the difference between men and women. It is unclear in the question whether you complain of this state of affairs (that probably refers to contemporary United States) or you ask what is the underlying moral principle that justifies it. If it is the second one, I would say that there is no such a principle.

That parental discipline may constitute a form of abuse depends entirely on what you accept under the label of "discipline". Consider for example a family in which following some religious practices - like preying before supper, or not eating certain kinds of food - is considered as part of a discipline that children are obliged to follow, and a 10 years old child (that is, someone who is cognitively able to take at least partly autonomous decisions on her moral preferences, even is she still doesn't have reached the institutionally established "age of reason", usually 16, 18 or 21 according to the countries) who refuses to comply. In this case, I would consider a sanction of her behaviour as a form of abuse. Punishing her for not complying to a rule she doesn't want to endorse because she finds it incompatible with her ideas and moral feelings is a form of abuse. Abusing children means prescribing them a system of rules of disciplines without taking their stance and thinking about what is...